Has anyone checked or replaced the coil? Maybe this is your problem with the truck,just another possibility to look at,with the engine running take a spray bottle of water and wet down the coil and see if you get any arcing or if it starts missing. might have a crack or carbon tracking in the coil someplace that acts up at times
Have you done a compression check on the engine,to see what the compression is like?
Is there an LP injector/injectors on the truck? Possibly an injector sticking closed? Just because there is a miss dosent mean that it is Igniton system related,it is the highest probabliity but not the only thing to look at.
One other thing has any one checked the pickup in the distributor????